diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 5e906ea..9a5eb76 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -588,6 +588,7 @@ static enum drm_mode_status mode_valid_path(struct drm_connector *connector,
  * &drm_crtc_state.connectors_changed is set when a connector is added or
  * removed from the crtc.  &drm_crtc_state.active_changed is set when
  * &drm_crtc_state.active changes, which is used for DPMS.
+ * &drm_crtc_state.no_vblank is set from the result of drm_dev_has_vblank().
  * See also: drm_atomic_crtc_needs_modeset()
  *
  * IMPORTANT:
@@ -654,6 +655,11 @@ static enum drm_mode_status mode_valid_path(struct drm_connector *connector,
 
 			return -EINVAL;
 		}
+
+		if (drm_dev_has_vblank(dev))
+			new_crtc_state->no_vblank = false;
+		else
+			new_crtc_state->no_vblank = true;
 	}
 
 	ret = handle_conflicting_encoders(state, false);
@@ -2202,7 +2208,9 @@ void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *old_state)
  * when a job is queued, and any change to the pipeline that does not touch the
  * connector is leading to timeouts when calling
  * drm_atomic_helper_wait_for_vblanks() or
- * drm_atomic_helper_wait_for_flip_done().
+ * drm_atomic_helper_wait_for_flip_done(). In addition to writeback
+ * connectors, this function can also fake VBLANK events for CRTCs without
+ * VBLANK interrupt.
  *
  * This is part of the atomic helper support for nonblocking commits, see
  * drm_atomic_helper_setup_commit() for an overview.
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 552ec82..c98ed814 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -69,6 +69,12 @@
  * &drm_driver.max_vblank_count. In that case the vblank core only disables the
  * vblanks after a timer has expired, which can be configured through the
  * ``vblankoffdelay`` module parameter.
+ *
+ * Drivers for hardware without support for vertical-blanking interrupts
+ * must not call drm_vblank_init(). For such drivers, atomic helpers will
+ * automatically generate fake vblank events as part of the display update.
+ * This functionality also can be controlled by the driver by enabling and
+ * disabling struct drm_crtc_state.no_vblank.
  */
 
 /* Retry timestamp calculation up to 3 times to satisfy
@@ -489,6 +495,28 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
 EXPORT_SYMBOL(drm_vblank_init);
 
 /**
+ * drm_dev_has_vblank - test if vblanking has been initialized for
+ *                      a device
+ * @dev: the device
+ *
+ * Drivers may call this function to test if vblank support is
+ * initialized for a device. For most hardware this means that vblanking
+ * can also be enabled.
+ *
+ * Atomic helpers use this function to initialize
+ * &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset().
+ *
+ * Returns:
+ * True if vblanking has been initialized for the given device, false
+ * otherwise.
+ */
+bool drm_dev_has_vblank(const struct drm_device *dev)
+{
+	return dev->num_crtcs != 0;
+}
+EXPORT_SYMBOL(drm_dev_has_vblank);
+
+/**
  * drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC
  * @crtc: which CRTC's vblank waitqueue to retrieve
  *
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 408b6f4..ebcce95 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -175,12 +175,25 @@ struct drm_crtc_state {
 	 * @no_vblank:
 	 *
 	 * Reflects the ability of a CRTC to send VBLANK events. This state
-	 * usually depends on the pipeline configuration, and the main usuage
-	 * is CRTCs feeding a writeback connector operating in oneshot mode.
-	 * In this case the VBLANK event is only generated when a job is queued
-	 * to the writeback connector, and we want the core to fake VBLANK
-	 * events when this part of the pipeline hasn't changed but others had
-	 * or when the CRTC and connectors are being disabled.
+	 * usually depends on the pipeline configuration. If set to true, DRM
+	 * atomic helpers will send out a fake VBLANK event during display
+	 * updates after all hardware changes have been committed. This is
+	 * implemented in drm_atomic_helper_fake_vblank().
+	 *
+	 * One usage is for drivers and/or hardware without support for VBLANK
+	 * interrupts. Such drivers typically do not initialize vblanking
+	 * (i.e., call drm_vblank_init() with the number of CRTCs). For CRTCs
+	 * without initialized vblanking, this field is set to true in
+	 * drm_atomic_helper_check_modeset(), and a fake VBLANK event will be
+	 * send out on each update of the display pipeline by
+	 * drm_atomic_helper_fake_vblank().
+	 *
+	 * Another usage is CRTCs feeding a writeback connector operating in
+	 * oneshot mode. In this case the fake VBLANK event is only generated
+	 * when a job is queued to the writeback connector, and we want the
+	 * core to fake VBLANK events when this part of the pipeline hasn't
+	 * changed but others had or when the CRTC and connectors are being
+	 * disabled.
 	 *
 	 * __drm_atomic_helper_crtc_duplicate_state() will not reset the value
 	 * from the current state, the CRTC driver is then responsible for
@@ -336,7 +349,14 @@ struct drm_crtc_state {
 	 *  - Events for disabled CRTCs are not allowed, and drivers can ignore
 	 *    that case.
 	 *
-	 * This can be handled by the drm_crtc_send_vblank_event() function,
+	 * For very simple hardware without VBLANK interrupt, enabling
+	 * &struct drm_crtc_state.no_vblank makes DRM's atomic commit helpers
+	 * send a fake VBLANK event at the end of the display update after all
+	 * hardware changes have been applied. See
+	 * drm_atomic_helper_fake_vblank().
+	 *
+	 * For more complex hardware this
+	 * can be handled by the drm_crtc_send_vblank_event() function,
 	 * which the driver should call on the provided event upon completion of
 	 * the atomic commit. Note that if the driver supports vblank signalling
 	 * and timestamping the vblank counters and timestamps must agree with
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
index 4d89cd0..df615eb 100644
--- a/include/drm/drm_simple_kms_helper.h
+++ b/include/drm/drm_simple_kms_helper.h
@@ -100,8 +100,11 @@ struct drm_simple_display_pipe_funcs {
 	 * This is the function drivers should submit the
 	 * &drm_pending_vblank_event from. Using either
 	 * drm_crtc_arm_vblank_event(), when the driver supports vblank
-	 * interrupt handling, or drm_crtc_send_vblank_event() directly in case
-	 * the hardware lacks vblank support entirely.
+	 * interrupt handling, or drm_crtc_send_vblank_event() for more
+	 * complex case. In case the hardware lacks vblank support entirely,
+	 * drivers can set &struct drm_crtc_state.no_vblank in
+	 * &struct drm_simple_display_pipe_funcs.check and let DRM's
+	 * atomic helper fake a vblank event.
 	 */
 	void (*update)(struct drm_simple_display_pipe *pipe,
 		       struct drm_plane_state *old_plane_state);
diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h
index 9fe4ba8..2559fb9 100644
--- a/include/drm/drm_vblank.h
+++ b/include/drm/drm_vblank.h
@@ -195,6 +195,7 @@ struct drm_vblank_crtc {
 };
 
 int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs);
+bool drm_dev_has_vblank(const struct drm_device *dev);
 u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
 u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
 				   ktime_t *vblanktime);
